1. Field of the Invention
The present invention is directed to a projection apparatus and more particularly to a projection apparatus capable of projecting an image having a plurality of sub imaging regions arranged in an array.
2. Description of Related Art
In recent years, due to a combination with mobile projection demands, a pico projection apparatus may be further widely applied in various fields, such as home, business, traveling, games, mobility and so on and has become one of the most important technologies to be developed in the projection apparatus field.
Generally, a pico projection apparatus is referred to a portable projector which is weighted under 1 kilogram. The projection technologies that are widely applied to pico projection apparatuses include the LCD projection technology, the liquid crystal on silicon (LCoS) projection technology, the digital light processing (DLP) projection technology and the laser scanner projection technology. Therein, the laser scanner projection technology has advantages, such as high luminance, wide color gamut, focus-free and long lifespan due to the usage of a laser source. On the other hand, the laser scanner projection technology applies a micro-electro-mechanical system (MEMS) to fabricate related mirror elements and systems and thus, also has advantages, such as being small-volume, light-weight, having low power consumption and stable functionality, etc. Moreover, a laser scanner projection apparatus may be embedded into a mobile device due to being small-volume and become more convenient in carrying.
However, the laser light source adopted by the laser scanner projection technology has characteristics, such as having high collimation, small divergence angles, etc., and thus, when the laser light source used by the laser scanner projection technology is directly incident on a human eye, a permanent damage will be caused on a retina. Accordingly, every country in the world sets up safety criteria on the usage of the laser light source. For instance, according to the laser safety criteria “ICE 60825-1 2000” set up by the International Electrotechnical Commission (IEC), it is regulated that an output power of a continuous-wave visible laser beam is not allowed to be greater than 1 milliwatt (MW). However, if doing so, an image luminance capable of being outputted by the laser scanner projection technology is limited.
Moreover, an image resolution which may be achieved by the laser scanner projection technology is also decided by a size and a rotation speed of an MEMS mirror. Typically, when the MEMS mirror has a greater size or a faster rotation speed, the image resolution will be higher. However, the greater size of the MEMS mirror leads to more limitations to the rotation speed, while the smaller size of the MEMS mirror leads to higher cost. As a result, the rotation speed and the size of the MEMS lens are not easily improved simultaneously, which also construct limitations to an image resolution that can be achieved by the laser scanner projection technology.
Accordingly, in order to meet requirements on both mobile projection and quality of projected images, how to overcome technological bottlenecks in the laser scanner projection technology is indeed one of the important subjects for research and design staffs to pay attention to.